Field of the Invention
The present invention relates to a metal foil pattern layered body, a metal foil layered body, a metal foil multi-layer substrate, solar a cell module, and a method of manufacturing a metal foil pattern layered body.
Particularly, the present invention relates to a metal foil pattern layered body used to electrically connect so-called back contact solar cells to each other, and a solar cell module using the metal foil pattern layered body.
Additionally, the present invention relates to: a metal foil pattern layered body including a metal foil on which electroconductive patterns including a wiring pattern, a circuit pattern, or the like are provided, an insulating layer, and a base member on which they are layered; and a solar cell module in which a solar cell is provided on and sealed by the metal foil pattern layered body.
Moreover, the present invention relates to: a metal foil layered body in which a metal foil having a wiring pattern is stacked on a base member; and a solar cell module in which a solar cell is connected to and sealed by a metal foil layered body.
Description of the Related Art
In recent years, the spread of photovoltaic power generation, that is a power generation system utilizing natural energy, rapidly proceeds.
As shown in FIG. 27, a solar cell module generating photovoltaic power includes: a light-transmissive substrate 502 disposed on a surface to which light is incident; a back sheet 501 disposed on the back face side located on the opposite side of the light incidence surface; and a plurality of solar cells 503 disposed between the light-transmissive substrate 502 and the back sheet 501.
In addition, the solar cells 503 are sandwiched and sealed between a seal member 504 made of an ethylene-vinyl acetate copolymer (EVA) film or the like.
Conventionally, in a solar cell module, a plurality of solar cells 503 are electrically connected in series to wiring members 505 having a width of 1 to 3 mm.
The solar cell 503 has a structure in which a negative electrode (N-type semiconducting electrode) is provided on a top face side serving as a light-receiving face of sunlight and in which a positive electrode (P-type semiconducting electrode) is provided on the back face side.
Consequently, when the solar cells 503 adjacent to each other are connected through the wiring members 505, the wiring members 505 overlap the light-receiving face of the solar cell 503, and the area efficiency of photoelectric conversion thereby tends to be degraded.
Accordingly, in response to this, for example, Japanese Unexamined Patent Application, First Publication No. 2009-111122 proposes a back contact solar cell in which both a positive electrode and a negative electrode are provided on the back face of a solar cell, and the electrodes are electrically connected to each other through a circuit layer provided on a substrate.
The solar cell employing this system can connect a plurality of solar cells in series on the back face of the cell, the light-receiving area of the top face of the cell does not sacrifice, it is possible to prevent the area efficiency of photoelectric conversion from being degraded.
Additionally, a plurality of the solar cells are electrically connected through to a metal foil pattern layered body which is placed at the back face side of the solar cells.
That is, the metal foil pattern layered body forms a layered structure in which a metal foil pattern is formed on a base member, and the solar cells are electrically connected to each other as a result of using the metal foil pattern as a circuit layer.
As a technique of forming the metal foil pattern in the above-described metal foil pattern layered body, a chemical-milling by etching have been used.
In this technique, a resist material or the like having etch resistance are patterned on a metal foil, thereafter, immersion in an etching solution or the like is carried out, as a result, a part of the metal foil at which the resist material is not formed can be removed.
In contrast, in this technique, patterning of the resist material is necessary, there is a problem in that the patterning of the resist material is difficult in accordance with a large-scaled metal foil.
Additionally, since a large amount of etching solution for chemically milling a metal foil is used, installation of a facility required for processing the etching solution and a large amount of cost required for environmental measures or the like are necessary.
As another technique of patterning a metal foil in order to solve the above-mentioned problem, for example, a punching process with a blade of a die as disclosed in Japanese Patent No. 3116209 have been developed.
Depending on the types of die, there is a difference in durability, shape accuracy, and a machining area; however, in recent years, on demand for improvement of the degree of precision and increase in area of a die, it is possible to carry out microscopical patterning such as approximately several hundreds of μm.
Additionally, not only the conventional solar cell module shown in FIG. 27, a solar cell module provided with bilayer seal films has also been conventionally known.
Specifically, such solar cell module shown in FIG. 28 includes: a light-transmissive substrate 620 disposed on a face to which light is incident; a solar cell module base member 610 (back sheet) disposed on a back face side located on a side opposite to the light incidence surface; and a plurality of solar cells 630 sealed between the light-transmissive substrate 620 and the solar cell module base member 610.
Moreover, the solar cells 630 is sealed and sandwiched between seal films 640a and 640b formed of an ethylene-vinyl acetate copolymer (EVA) film or the like.
Conventionally, in a solar cell module, a plurality of solar cells 630 are electrically connected in series to wiring members 650.
The solar cell 630 has a structure in which a negative electrode 631 is provided on a top face side serving as a light-receiving face 630a of sunlight and a positive electrode 632 is provided on the back face side.
Consequently, when the solar cells 630 adjacent to each other are connected through the wiring members 650, the wiring members 650 overlap the light-receiving face 630a of the solar cell 630, and there is a drawback in that the area efficiency of photoelectric conversion is degraded.
In addition, according to the arrangement of the aforementioned electrodes 631 and 632, since the solar cell module has a structure in which the wiring members 650 come around behind the solar cells 630 from the upper side thereof, there is a concern that the wiring members 650 are broken as a result of a difference in the coefficient of thermal expansion between parts constituting the solar cell module.
Consequently, Japanese Unexamined Patent Application, First Publication No. 2009-111122 and Japanese Unexamined Patent Application, First Publication No. 2005-11869 propose a back contact solar cell in which both a positive electrode and a negative electrode are provided on the back face of the cell.
The solar cell employing this system can connect a plurality of solar cells in series on the back face of the cell, the light-receiving area of the top face of the cell does not sacrifice, it is possible to prevent a reduction in the light receiving efficiency and the area efficiency of photoelectric conversion.
Furthermore, since it is not necessary to adopt the structure in which the wiring members come around behind the solar cells from the upper side thereof, it is also possible to prevent breaking of the wiring members which is due to a difference in the coefficient of thermal expansion between parts forming the solar cell module.
Regarding the above-described solar cell modules, components may be placed on the market, which is formed by coating (lamination) a solar cell back sheet with a layered body that is coated with a metal foil having a circuit pattern (wiring pattern) used to connect solar cells to a top face of an insulating base member with an adhesive layer interposed therebetween.
For example, in a back sheet 610 which is used as a solar cell module base member shown in FIG. 29, a layered body is stacked on the top face of the back sheet 610, and the layered body is configured by adhesively attaching a metal foil 603 having a circuit pattern formed thereon to a base member 601 with an adhesive layer 602 interposed therebetween.
Regarding this layered body, when the circuit pattern is formed on the metal foil 603, a photoresist is applied on a sheet-shaped metal foil 603, a mask having the same pattern as the circuit pattern is mounted on an exposure apparatus, and exposure is carried out.
Thereafter, unnecessary resist is removed, etching through the resist pattern provided on the metal foil 603 is carried out, and a predetermined circuit pattern is thereby formed on the metal foil 603.
In the circuit pattern of the resultant metal foil 603 in this manner, as shown in FIG. 29, the edge face of the metal foil 603 is perpendicularly cut off by etching.
Additionally, as a metal foil pattern layered body forming a circuit pattern serving as an electroconductive pattern, a constitution has been proposed as disclosed in Japanese Unexamined Patent Application, First Publication No. 2007-76288.
The metal foil pattern layered body is a metal foil sheet in which an adhesive layer and a metal foil are stacked in layers on a top face of the base member, a metal foil is punched with a heated punching blade, unnecessary portions are removed, a circuit pattern of the temporarily-fixed metal foil is thermal-pressure bonded to the base member by use of a die or the like, and a metal foil pattern layered body is thereby formed.
In this manner, the metal foil sheet is utilized, for example, to manufacture of an antenna of an integrated circuit tag.
In this case, the edge face of the metal foil having the circuit pattern is also vertically cut off with a punching blade as shown in FIG. 29.
Moreover, not only the above-described back sheet shown in FIG. 29, but also, for example, a back sheet FIG. 30 is known.
In a back sheet 610 which is used as a solar cell module base member shown in FIG. 30, a layered body 604 is stacked on the top face of the back sheet 610, and the layered body is configured by adhesively attaching a metal foil 603 having a wiring pattern 603a formed thereon to a base member 601 with an adhesive layer 602 interposed therebetween.
Regarding this layered body 604, when the wiring pattern 603a of the metal foil 603 is formed, a photoresist is applied on a sheet-shaped metal foil 603, a mask having the same pattern as the wiring pattern 603a is mounted on an exposure apparatus, and exposure is carried out.
Thereafter, unnecessary resist is removed, etching through the resist pattern provided on the metal foil 603 is carried out, and a predetermined wiring pattern 603a is thereby formed on the metal foil 603.
In the wiring pattern 603a of the resultant metal foil 603 in this manner, as shown in FIG. 30, the edge face of the metal foil 603 is perpendicularly cut off by etching.
Additionally, as a metal foil layered body having a wiring pattern, a constitution has been proposed as disclosed in Japanese Unexamined Patent Application, First Publication No. 2007-76288.
In the metal foil layered body, a metal foil is stacked in layers on a top face of the base member with an adhesive layer interposed therebetween, a metal foil is punched with a heated punching blade, unnecessary portions are removed, a wiring pattern of the temporarily-fixed metal foil is thermal-pressure bonded to the base member by use of a die or the like, and a metal foil pattern layered body is thereby formed.
In this manner, the metal foil layered body is utilized for manufacture of an antenna of an integrated circuit tag.
In this case, the edge face of the metal foil having the wiring pattern is also vertically cut off with a punching blade as shown in FIG. 30.
However, in the case of die-cutting the metal foil which is stacked on the base member with the adhesive layer interposed therebetween, it is necessary remove an unnecessary region, that is an unnecessary portion of the metal foil, from the adhesive layer after the die-cutting.
In the case where the unnecessary region of the metal foil is formed on the adhesive layer integrally with the adhesive layer, it is possible to continuously remove the unnecessary portion by, for example, winding up.
Furthermore, in the case of die-cutting the metal foil which is stacked on the base member with the adhesive layer interposed therebetween, it is necessary remove an unnecessary region, that is an unnecessary portion of the metal foil, from the adhesive layer after the die-cutting.
Moreover, it is thought that the metal foil pattern is removed from the base member due to aged deterioration, it is desired to further improve durability.
However, when the winding up is carried out, there is a concern that not only the unnecessary region of the metal foil but also a necessary region that is to be left as a metal foil pattern is removed.
Additionally, it is thought that the metal foil pattern is removed from the base member due to aged deterioration, it is desired to further improve durability.
In addition, when die-cutting is performed using a blade die, a cutting depth of the blade is suitably set; however, if the cutting edge of the blade does not reach the back face of the metal foil, it is not possible to reliably cut the metal foil.
On the other hand, if a cutting depth of the blade is excessively large, the cutting edge of the blade damages to the top face of the base member, product reliability is degraded.
For this reason, in order to avoid the base member from damage while reliably cutting the metal foil, it is necessary to strictly set a cutting depth to stop the cutting edge of the blade in the adhesive layer.
However, the thickness of the adhesive layer is thin such as approximately 10 μm, it is difficult to adjust the cutting depth.
Additionally, regarding the metal foil pattern layered bodies shown in FIGS. 28 and 29, in the case of forming a circuit pattern on the metal foil by etching, a large amount of chemical solutions or materials such as resists such as photoresists or the like, etching solution, remover for remaining resists, or the like is necessary, it is complicated, and the cost of manufacturing is high.
Furthermore, there is a defect that a metal foil or the like may be damaged due to use of chemical solutions such as etching solution, resist remover, or the like.
Moreover, in the case where a circuit pattern is manufactured by not only etching but also punching a metal foil with a punching blade, an edge face of the circuit pattern of the metal foil is formed vertical to the base member and, and there is a concern that the insulating layer is removed from the metal foil of circuit pattern when stacking an insulating layer on the circuit pattern. Therefore, the metal foil pattern layered body may be defective.
Furthermore, in the case where a solar cell module or the like is manufactured using the aforementioned metal foil pattern layered body, a constitution is employed in which a seal member is formed on the top face of the circuit pattern, the solar cells are packaged inside the seal member, and the electrodes provided on the back faces of the solar cells are connected to the circuit pattern.
Consequently, since the edge face of the circuit pattern of the metal foil is vertically formed, the seal member sealing the solar cells may be removed from the metal foil of the circuit pattern, and displacement of the seal member with respect to the metal foil of the circuit pattern may occur; contact failure between the electrode of the solar cell and the electrode of the circuit pattern, which is due to misalignment, may occur.
Additionally, regarding the metal foil layered bodies having the wiring pattern shown in FIGS. 28 and 30, in the case of forming a wiring pattern on the metal foil by etching, a large amount of chemical solutions or materials such as resists, etching solution, remover for remaining resists, or the like is necessary, it is complicated, and the cost of manufacturing is high.
Furthermore, after a wiring pattern is formed by etching, punching, or the like, the cross-sectional configuration of the edge face of the metal foil having the wiring pattern is a shape which is formed vertical to the base member.
Consequently, for example, as shown in FIG. 30, when electroconductive paste 600 such as solder or the like is mounted on the upper face of the metal foil 603 forming the wiring pattern 603a, thereafter, the electroconductive paste 600 is melt by heating and is connected to the electrodes or the like of the back faces of the solar cells, the high-temperature solder flows out from the upper face of the metal foil 603 toward adjacent wiring pattern 603a, there is a concern that the wiring patterns 603a are short-circuited.